Metal tube.



BEST AVAlLABLE CO No. 807,264. PATENTED DEC. 12, 190

E. T. GREBNPIELD.

METAL TUBE.

APPLICATION FILED DEGJZ, 1904.

INVENTOR By his Altarnqy, 1 M 9 WITNESSES:

BEST AVAILABLE cop UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

Patented Dec. 12, 1905.

Application filed December 12, 1904. Serial No. 236,686-

To all whom it may concern.-

Be it known that I, EDWIN T. GREENFIELD, a citizen of theUnited States,residing at Monticello, county of Sullivan, and State of New York, havemade a new and useful Invention in Metal Tubes, of which the followingis a specification.

My invention is directed particularly to improvements in metal tubesformed from ironor other skelps; and it has forits objects, first, toconstruct a tube of this nature with an absolutely steam and gas tightseam or joint, and, second, to construct such a tube with an interiorlining integral with the face thereof which shall be substantiallynon-oxidizable.

Prior to my invention it was old in the art to construct skelp-bent orskelp-drawn tubes by welding the seam or joint after the tube had beenformed; It was also old, broadly, to effect a steam-tight joint bybrazing the edges together, but, so far as I am aware, not withoutmaterial waste of the brazing material.

My invention therefore consists in the novel tube hereinafter described,and illustrated in the accompanying drawings.

In a prior application, bearing Serial No. 219,606, filed in the UnitedStates Patent Offi'ce on the 5th day of August, 1904, I have disclosed amethod of and means for making tubes from metal skelps by drawing thesame through successive forming-rolls and simultaneously embedding inthe outer face thereof one or more strips of brazing material wherebythe completed tube may be surrounded by a screw-thread and integrallybrazed to the body thereof, my intention being at the time that theaforesaid invention was completed to provide suflicient brazing materialnot only to secure the thread to the body of the tube, but also to unitethe adjoining edges of the completed tube together, so as to constitutea steam and gas tight tube. I have ascertained in practice, however,that when-thetube is constructed in accordance with the beforementionedprocess the brazing material escapes through the seam and intotheinterior of the tube, and, furthermore, such a method or process astherein described necessitates the use of a greater amount of brazingmaterial than would be required to manufacture a simple tube without asurrounding screwthread. It was therefore with a view of providing askelp-drawn tube which should have the seam at the adjoining edgesthereof effectually sealed by a strip of metal brazed thereto and alsowith a further view of utilizing a portion of the brazing material forthe purpose of coating the interiorof the tube with a relatively nonoxidizable integral lining that the present invention was devised. Tubesof this nature have an especial utility in connection with electricwiring in buildings,&c., the rules of the boards of fire un derwritersnow requiring generally that metal armor-tubes which surround electricwires shall be interiorly comparatively non oxidizable.

My invention will be fully understood by referring to the accompanyingdrawings, in which- Figure l'represents a metal skelp having two groovesin its lateral edges and two grooves in one face with brazing materialembedded therein. Fig. 2 represents a cross- -section of apartially-completed tube constructed from the skelp illustrated in Fig.1, a sectional view being also shown of a metal sealing-strip located inposition for effectually sealing the seam. Fig. 3 represents a similarsectional view of a completed tube with the brazing material as itappears after the tube has been subjected to heat and pressure,illustrating also the lining of non-oxidizable brazing material inposition and integral with the inner face of the tube.

The method of constructing this tube is as 7 follows: A metal skelp ispassed through a machine having laterally-disposed V-shaped rollers likethose disclosed in my before-mentioned application for giving to itslateral edges V-shaped grooves, so that the outer or extended portionsthereof assume the construction illustrated at 6 and c, for a purpose tobe hereinafter described. Simultaneously additional grooves d, one ormore in number, preferably two, are cut by one or more rapidly-rotatingsaws or V-shaped scoringrolls at such points as may be most advisable,preferably so that they will be ninety degrees from the seam when thetube is partially completed, as shown in Fig. 2. After the severalgrooves have been formed in the sides and face of the skelp brass orother brazing wires g are embedded in the lateral grooves, and

similar wires or strips of brazing material e are embedded in thegrooves (Z and firmly sel departed from and still come within the see;

cured therein prior to the forming of the slzelp into tubular shape,said brazing wires or strips having been previously passed through aliquid flux, as disclosed in a prior patent granted 1903, and numbered727,128. The skelp is then passed through a slcelp-bender or tubeformingmachine for forming tubes from 'slzelps such, for instance, as isdisclosed in my before-mentioned application-in such manner as-toinclose the grooves (Z and their containing brazing material within thetube. At the same time a sealing-strip f of metal, pref.-

.erablyof the conformation shown in Fig. 2 of the drawings and of thesame material as that of the tube, is guided into position between theprojections 0 and I), the structure up to this point being substantiallyas illustrated in Fig. 2. In the succeeding steps of formation it issubjected to the action of an internallydisposed mandrel and one or moreexternally disposed rolls in a manner well understood by those skilledin the art of tube-drawing, so as to firmly force theinternally-disposed projections c 0 outward andthe externally-disposedprojections 6 Z) inward and give to the tube complete cylindricalformation. It is then brought to white heat in a furnace for a definitelength of time with the seam down' wardly located in such manner as toenable the brazing material 6 to accumulate in the lower side of thetube and permeate the seam, so as to thereby seal it in the manner shownin Fig. 3. At the same time the fused material from the wires 9 efl'ectually seals the joint at the sides of the 'stripf. The tube isnow: rotated fora definite length of time while itis allowed to cool,thus forming within the interior surface thereof a relativelynon-oxidizable coating, as clearly shown in Fig. 3, it being understood,of course, that the grooves dare of such depth and width as to containsufficient material for this purpose, the dimensions of said groovesbeing regulated by the thickness of the lining it is desired to placewithin the inner surface. a

I am aware that it has been heretofore proposed to dispose a strip ofbrazing material covered with a flux between the adjoining edges of askelp-drawn tube and afterward heat the same to such an extent as toetl'ectually braze the adjoining parts together, and I make no claimhereinafter broad enough to include such a tube, my most generic claimin this particular being directed to a skelp-drawn tube in which theadjoining edges are firmly secured together by a sealing-strip,prefer-ab] y of the same metal as that of which the tube is constructed.

I do not limit the product herein disclosed to the especial details ofconstruction whereby 1t is produced, as these might be materially t meon the 5th day of May, to effectually confine the same securelytherejoining edges,

' of the tube and all of of my claims hereinafter made. I believe isbroadly new with meto effect the closur. of the seam of a skelp-bent orskelp-drawn tube by embeddinga sealing-strip in grooves in the lateraledges thereof as it is bent and in in the manner shown in Fig. 3 of thedrawings, whether the same be brazed or not. believe it is also broadlynew with me to effect the junction of the adjoining edges of a skelpbentor skelp-drawn tube by providing a sealing-strip between said edges andembedded therein and effecting a steam and gas tight sealing of the samethrough the agency of a brazing material located within the tube wherebynone of the brazing material is allowed to escape and also that it isnew with me to simultaneously braze the adjoining edges of a skelp-bentor skelp-drawn tube and line the interior thereof with 'a'subs'tantiallynonoxidizable medium. 1

Although I prefer to use a flux as described, this is notalwaysnecessary.

Having thus described my invention, what I claim, and desire to secureby Letters Patent of the United States, is-

1. Atube formed from a skel p of metal having a sealing-strip embeddedin grooves in the adjoining edges.

2. A tube formed from a skelp of metal having a sealing-strip embeddedin triangular grooves in the adjoining edges and integrally unitedthereto by brazing material.

3. Atube formed from a skelp of metal having a sealing-strip embeddedbetween the adjoining edges, the interior of said tube and the adjacentinterior parts of the edges and sealing-strip being lined with brazingmaterial.

4. A tube formed from a skelp of metal having a sealing-strip embeddedbetween the adjoining edges, the tube boing coated throughout itsinterior with a relatively non oxidizable metal. V

5. A tube formed from a skelp of metal having a sealing-strip embeddedbetween the adsaid tube being interiorl y lined witha relativelynon-oxidizable metal and the adjoining edges of the tube and thesealingstrip also coated with brazing material.

6. A tube formed from a skelp of metal having its edges connectedtogether by a sealingstrip and a fusible brazing metal.

7. A tube'formed from a skelp of metal having its edges connectedtogether by a sealingstrip f of greater thickness at its lateral edgesthan at its center, the edges of the sealingstrip being embedded in theadjoining edges said parts firmly locked together.

8. Atube formed from a skelp of metal having its edges united togetherby a lockingstrip of metal, the lateral edges of the locking- BESTAVAiLABLE coP being securely embedded in the adjoin- In testimonyWhereofIhavesigned my name iges of the tube. A tibe formed Cfrom a skelpof metal havscribing witnesses.

.ig its e ges unite toget1er by a ocking- J strip of metal, the lateraledges of the locking- EDWIN GREENFIELD' strip being securely embedded inthe adjoin- Witnesses: ing edges of the tube and united together by C.J. 1(IN'I'NER, a brazing material. M. T. KEATING.

to this specification in the presence of two sub- IO

